Fish Oil Primer: Essential Information.

Omega-3 and omega-6 fatty acids are termed essential fatty acids because they cannot be manufactured by the body. Therefore, they must be consumed from dietary sources. Omega-6s are derived from many different kinds of plant and animal products. Omega-3s come primarily from fatty fish, such as salmon, mackerel, and tuna, and, to a lesser extent, walnuts and flaxseed, but they are not as broadly available in the natural human diet as omega-6s. Both are polyunsaturated fatty acids, (PUFAs) but they differ slightly from each other in their chemical structure.

Compared with the diets of previous generations, modern diets contain significantly less omega-3 fatty acids and significantly more omega-6 fatty acids. For most people, a 4:1 ratio of omega-6 to omega-3 fatty acids may be optimal. To ensure a better balance of fatty acids in the diet, it has been suggested to increase the consumption of pre-formed EPA and DHA from fish and/or fish oils, increase the intake of ALA from plant foods, and decrease the intake of linoleic acid (LA), an omega-6 fatty acid found in meat, dairy, eggs, vegetable oils, corn, soy and other grains.

Alpha-linolenic acid (ALA) is the essential precursor to the omega-3 series of fatty acids found in various nuts and seeds, vegetable oils, and to a lesser extent in green leafy vegetables. Some people believe plant sources of ALA provide an adequate source of omega-3, but the majority of ALA is used for energy; only a very small percentage of ALA is metabolized to omega-3 fatty acids eicosapentanoic acid (EPA), and docosahexaenoic acid (DHA).[1] Additionally, it’s important to remember that individuals vary in their ability to convert ALA to omega 3 fatty acids, and that genetics, stress and diet all play a role. Therefore, consuming more fish, or taking fish oil supplements provides pre-formed omega-3s that are immediately available for use in the body.

After ingestion, fatty acids are dispersed into small particles by the action of the bile, hydrolyzed by digestive enzymes, and absorbed through the intestinal mucosa. Fatty acids are then distributed throughout the body where they are either converted into energy, stored as triglycerides, incorporated into cellular membranes, or combine to form longer fatty acids.

EPA and DHA are the two omega-3 polyunsaturated fatty acids most commonly discussed because decades of research have shown them to yield important health benefits for every cell, organ, and system in the body.

These essential fatty acids play a significant role in many biological structures and functions including: the stimulation of growth and reproduction; the health and growth of skin and hair; wound healing; plasma lipid levels; reducing platelet aggregation; as a precursor of all main eicosanoids; regulation of gene function; neural development; cardiac function; involvement in ion transport; structural units of cell membranes, mitochondria, and nuclei; and play a vital role in the properties of most membranes, improving cell membrane fluidity.²

In addition, omega-3 fatty acids impact free radical activity which is believed to play a role in cardiovascular disease, inflammatory conditions, obesity, mood and cognition, and cancer.^{3 4} Therefore, incorporating omega-3 fatty acids, through dietary intake or supplementation, may positively impact health.*

Omega-3 fatty acids are important in supporting a healthy response to inflammation by decreasing pro-inflammatory cytokine production. Because of this, a lower ratio of omega-6/omega-3 fatty acids appears to be more desirable in helping reduce the risk of many common conditions.

For example, altered fatty acid concentrations in the brain, due to dietary deficits in omega-3 and an abundance of omega-6 fatty acids, are thought to play a role in mood and cognition. Within brain membranes, PUFAs regulate neurotransmission, inflammation and oxidation, and neuroplasticity.⁵ In addition, an adequate dietary intake of omega-3 fatty acids, particularly DHA, is necessary for the growth of the brain, eyes, and nervous system during fetal development and infancy.

More than 60 double-blind studies have demonstrated that fish oil supplements are beneficial in supporting cardiovascular function and healthy blood pressure levels.⁶* The American Heart Association recommends that adults increase consumption of omega-3 fatty acids by consuming fatty fish a minimum of twice per week or 1 gram of EPA and DHA daily.⁷

It has been suggested that high doses of fish oil should be used with caution in people taking anticoagulant medication,⁸ and that fish oil supplementation may inhibit platelet aggregation and potentially increase the risk of bleeding. However, in no clinical trial has there been any evidence of increased blood loss due to ingestion of omega-3 fatty acids, and a recent systematic review states no need for discontinuation of fish oil supplements prior to surgery or other invasive procedures.⁹

Supplemental fish oil is primarily available as soft gel capsules and as liquids. When selecting a fish oil supplement, quality is key. Here are some factors to consider when selecting a fish oil supplement:

• Manufacturing standards. Is the fish oil manufactured according to international quality standards?
• Smell and taste. Fresh high quality fish oil does not smell or taste fishy.
• Sustainable fishing practices. Any environmentally responsible fish oil manufacturer should offer transparency into their fishing practices.
• Third-party test results for purity and freshness. A third-party certificate of analysis indicates the levels of purity from environmental toxins, and the oxidation level (or freshness) of the oil.

Fish oil supplements that comply with the stringent requirements of Good Manufacturing Practice (GMP) will have very low levels of mercury and other contaminants. This is because the fish oil is distilled or CO2 extracted to remove impurities.
Compared with the diets of previous generations, modern diets contain significantly less omega-3 fatty acids and significantly more omega-6 fatty acids. As a result, the incorporation of fish oil supplements has become an essential component of optimal health.

1 Lavado-Garcia J, Roncero-Martin R, Moran JM, et al. PLoS One. 2018;13(1):e0190539.
2 Abu-Salah KM, al-Othman AA, Lei KY. Br J Nutr. 1992;68:435-43.
3 Chow CK. Fatty acids in foods and their health implications. 3rd ed. Boca Raton: CRC Press; 2008.
4 Calder PC. JPEN J Parenter Enteral Nutr. 2015;39(1 Suppl):18S-32S.
5 Su KP, Matsuoka Y, Pae CU. Clin Psychopharmacol Neurosci. 2015;13(2):129-137.
6 Geleijnse J.M.; Giltay E.J.; Grobbee D.E.; et al. J Hypertens (2002) 20 1493–1499.
7 Krauss RM, Eckel RH, Howard B, et al. Stroke. 2000;31(11):2751-2766.
8 Watkins PA, & Benjamin C. Encyclopedia of human nutrition. Oxford: Elsevier;2005. p. 186-98.
9 Begtrup KM1, Krag AE, Hvas AM. Dan Med J. 2017 May;64(5).